which is corrected for statistical fluctuations in data by scaling with predicted values according to the recipe in Ref. [1]}. This form of \(\Delta _i^2\)  leads to a logarithmic term arising from likelihood transition of \(\chi ^2\) .
The minimization of \(\chi ^2\)  function against the fit parameters and the nuisance parameter is done using the package MINUIT [2]}, which is interfaced with XFITTER. The PDFs uncertainties arising from the uncertainties in the measurements are estimated using Hessian method [3]} adopting the same tolerance \(\Delta \chi ^2\)  = 1 as the HERA, ATLAS and CMS groups, corresponding to 68% confidence level (CL).
